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Wake-up frame structure. WF, wake-up frame. 

Wake-up frame structure. WF, wake-up frame. 

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A novel wake-up receiver for wireless sensor networks is introduced. It operates with a modified medium access protocol (MAC), allowing low-energy consumption and practical latency. The ultra-low-power wake-up receiver operates with enhanced duty-cycled listening. The analysis of energy models of the duty-cycle-based communication is presented. All...

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Citations

... The WuRx must be operated duty-cycled to ensure a low average energy consumption. Recent works introducing an LNA are [2,3]. Fig. 1 shows the common building blocks of different hardware architectures in the state of the art (SoA). ...
... To minimize energy consumption modern receivers are typically duty cycled [9]- [17], i.e., they listen only at predetermined time periods, and sleep otherwise. To alert the receiver of an incoming message, the transmitter sends a preamble either at the beginning of a listening period (e.g., [9], [17]- [19]), or immediately in which case the preamble is long enough to cover at least one listening period (e.g., [12], [15]). In both cases (as seen in [9], [12], [15], [17]- [19]) the receiver performs a binary hypothesis test, referred to as channel sensing, during the listening periods, to decide whether or not a preamble is present. ...
... To alert the receiver of an incoming message, the transmitter sends a preamble either at the beginning of a listening period (e.g., [9], [17]- [19]), or immediately in which case the preamble is long enough to cover at least one listening period (e.g., [12], [15]). In both cases (as seen in [9], [12], [15], [17]- [19]) the receiver performs a binary hypothesis test, referred to as channel sensing, during the listening periods, to decide whether or not a preamble is present. ...
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This paper proposes an energy-efficient detection scheme, referred to as AdaSense, that is particularly suitable in the sparse regime when events to be detected happen rarely. To minimize energy consumption, AdaSense exploits the dependency between the receiver noise figure (i.e., the receiver added noise) and the receiver power consumption; less noisy channel observations typically imply higher power consumption. AdaSense is duty-cycled and begins each cycle with a few channel observations in a low-power-low-reliability mode. Based on these observations, it makes a first tentative decision on whether or not a message is present. If no message is declared, AdaSense waits till the beginning of the next cycle and starts afresh. If a message is tentatively declared, AdaSense enters a confirmation second phase, takes more samples, but now in a high-power-high-reliability mode. If these observations confirm the tentative decision, AdaSense stops, else AdaSense waits till the beginning of the next cycle and starts afresh in the low-power-low-reliability mode. Compared to prominent detection schemes such as the clear channel assessment algorithm of the Berkeley Media Access Control (BMAC) protocol, AdaSense provides relative energy gains that grow unbounded in the small probability of false-alarm regime, as communication gets sparser. In the non-asymptotic regime, energy gains are 30% to 75% for communication scenarios typically found in the context of wake-up receivers.
... On the other hand, in [13], the authors proposed a wakeup receiver based on a tuned RF architecture that requires filtering for selectivity and high RF gain for high sensitivity. This architecture fits better due to its simplicity and low cost of implementation; it consists of an LNA to amplify the received signal with minimal noise, an envelope detector to downconvert the RF signal to a baseband with a significantly lower frequency than that of the carrier, a baseband amplifier to boost the voltage level of the extracted envelope, a hysteresis comparator, and a decoder. ...
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... The WuRx's sensitivity is limited due to the noise level of the passive diode detector circuit. Overcoming this limit, the implementation of [BDK18a] added a dutycycled low-noise amplifier (LNA) resulting in a sensitivity of −90 dBm. During active phase, the power consumption reaches over 1 mW. ...
... Operational amplifiers (OAs) are used as voltage amplifiers in implementations like [BDK18b; FSD21; Kaz+21]. [BDK18a] introduces a voltage amplifier with two bipolar junction transistors (BJTs). ...
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... A sensitivity of −71 dBm was achieved. The LNA-based design from [BDK18] utilizes bipolar junction transistor (BJT)based LNA and LF amplifier. The LNA amplifies 36 dB while only consuming 550 µA. ...
... The average power consumption is 3 µW while sensitivity is −90 dBm. Further improving the implementation of [BDK18], regarding average power consumption and sensitivity, is not the goal of this publication. Because of the utilization of a custom BJT-based LNAs, working in the sub-milliampere range, experimental results are very hard to reproduce. ...
... COTS LNAs are used in our proposed circuit, at the cost of a gain reduction and higher current demand. Further problems within the communication scheme of [BDK18] were detected, leading inevitably to a random packet loss. This publication introduces a special lowfrequency modulation and measurements were made to ensure no random packet loss occurs. ...
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... On the other hand, this affects the latency, reliability, and current consumption of the system. The authors in [30] used a two-stage LNA based on bipolar junction transistors (BJTs) and achieved a sensitivity of −90 dBm. However, the presented architecture means a higher circuitry effort due to numerous passive components. ...
... Table 1 summarizes the mentioned properties of the approaches from the SoA. Figure 2 shows an overview of the described WuRx architectures based on their power consumption, sensitivity, carrier frequency, and LF amplifiers. It can be seen that WuRx with RF amplifiers [29,30] achieves sensitivity better than −70 dBm with a power consumption of 8 µW. However, the integration of the LNA increases the average current consumption and the latency of the system compared to an always-on listening approach. ...
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... To perform this task, the WuRs are composed of an RF front-end and a digital baseband back-end, with a pattern recognizer or signal correlator used to identify the wake-up identifier. Power savings introduced by using WuRs are mostly observed in low-activity and low-average throughput applications, as the main radio interface is in sleep mode during a significant amount of time [4]. Due to its inherent simplicity, the on-off keying (OOK) modulation scheme is frequently the preferred option when designing a WuR. ...
... A common solution to improve the WuR's sensitivity consists of placing an LNA before the envelope detector to boost the signal-to-noise ratio (SNR), this architecture is known as tuned RF (TRF). A high gain is required from the LNA to reduce the contribution of the noise figure (NF) of the envelope detector, leading to a tradeoff between sensitivity and power dissipation [4]. To improve the circuit's interference resilience, high-Q off-chip components can be used to implement the input filter [13]. ...
... to a trade-off between sensitivity and power dissipation [4]. To improve the circuit's interference resilience, high-Q off-chip components can be used to implement the input filter [13]. ...
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... Nevertheless, recent developments have revealed exciting possibilities to enhan energy harvesting (EH) efficiency by designing suitable converters, combining converte in hybrid solutions, and adopting opportunities for wireless energy transmissio Developments in microelectronics enable significant energy savings, making an ener supply from ambient sources increasingly practicable. Wake-up receivers swit unnecessary system parts entirely off and reduce energy consumption during sleepi phases [4,5]. Data aggregation techniques [1], clustering, and intelligent routing realiz significant energy savings on the network level. ...
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... They demonstrate the feasibility of implementing a WuR with commercially available off-chip components by demonstrating a radio frequency envelope detection (RFED) WuR on a PCB mount. The most significant power consumption savings are observed when WuRs are used in low-traffic and low-density WSNs, mainly because the main transceiver is in the sleep mode for most of the time [11]. However, this type of customized platform is not cost-effective. ...
... Equation (10) shows the energy saving for the case where P k (T k ) = P s4 − P k in Equation (9) and subtracting the additional power consumption E TR . Equation (11) shows the amount of power saving. ...
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Wireless sensor nodes are heavily resource-constrained due to their edge form factor, which has motivated increasing battery life through low-power techniques. This paper proposes a power management method that leads to less energy consumption in an idle state than conventional power management systems used in wireless sensor nodes. We analyze and benchmark the power consumption between Sleep, Idle, and Run modes. To reduce sensor node power consumption, we develop fine-grained power modes (FGPM) with five states which modulate energy consumption according to the sensor node's communication status. We evaluate the proposed method on a test bench Mica2. As a result, the power consumed is 74.2% lower than that of conventional approaches. The proposed method targets the reduction of power consumption in IoT sensor modules with long sleep mode or short packet data in which most networks operate.
... To minimize energy consumption modern receivers are typically duty cycled [1]- [7], i.e., they listen only at predetermined time periods. To alert the receiver of an incoming message, the transmitter sends a preamble either at the beginning of a listening period (e.g., [1]- [3], [8]), or immediately in which case the preamble is long enough to cover at least one listening period (e.g., [6], [9]). In both cases the receiver performs a binary hypothesis test during the listening periods to decide whether or not a preamble is present. ...
... Indeed, as suggested in Section IV, the implementation overhead of AdaSense with respect to a non-adaptive receiver appears to be negligible. This suggests that duty cycled receivers, including the duty-cycled wake-up receivers [8], [9], [17], [29], could benefit from AdaSense. ...
... where (14) follows from the fact that the BMAC detection rule declares M = 1 if and only if Y i > η for i ∈ {1, . . . , n} and where (15) follows from (9). Similarly, we have ...
Preprint
Channel sensing consists of probing the channel from time to time to check whether or not it is active - say, because of an incoming message. When communication is sparse with information being sent once in a long while, channel sensing becomes a significant source of energy consumption. How to reliably detect messages while minimizing the receiver energy consumption? This paper addresses this problem through a reconfigurable scheme, referred to as AdaSense, which exploits the dependency between the receiver noise figure (i.e., the receiver added noise) and the receiver power consumption; a higher power typically translates into less noisy channel observations. AdaSense begins in a low power low reliability mode and makes a first tentative decision based on a few channel observations. If a message is declared, it switches to a high power high reliability mode to confirm the decision, else it sleeps for the entire duration of the second phase. Compared to prominent detection schemes such as the BMAC protocol, AdaSense provides relative energy gains that grow unbounded in the small probability of false-alarm regime, as communication gets sparser. In the non-asymptotic regime energy gains are 30% to 75% for communication scenarios typically found in the context of wake-up receivers.